This study will assess the use of interferon gamma-1b, instilled as drops, for the treatment of macular edema / cystic changes in participants with rod-cone dystrophy and enhanced S-cone syndrome. Up to 5 participants with rod-cone dystrophy and up to 5 participants with enhanced S-cone syndrome (12 years or older for each group) will be enrolled. Drops will be instilled four times daily for a total of two weeks. The follow-up period is one year with most of the visits occurring in the first eight weeks. Skin biopsy and blood samples will be obtained to help study the disease mechanisms using stem cell approaches.